Assuming you've set up the Model 1070's input to use that optical connection and it still didn't work, I can think of a few possibilities.

1. Bad optical cable. In this case, trying a different cable would be a good test.
2. Bad optical input on the 1070. In this case, trying a different optical input would be a good test.
3. Bad optical output on the Roku. Trying a different optical source with the same cable and input on the 1070 would be a good test.

All of these assume that there's no setting in the Roku that has disabled the optical output and no setting in the 1070 that has been overlooked. To check those, we should know what settings you have already adjusted on the Model 1070.